According to a wired networking technology of the related art, various devices should be connected to each other through cables, causing difficult installation and management.
A WPAN technology, which has been developed to overcome the limitations of such a wired networking technology, uses communication schemes such as Bluetooth, ZigBee and ultra wide band (UWB).
The WPAN is applied to an environment such as an indoor place, an office or a closed public place to provide a communication service. The WPAN is applied to various fields, for example, the field of industrial control for equipment monitoring and automation, the field of disaster management for recognition and location determination, the field of remote control, the field of automobile control related to a tire pressure sensor or in-vehicle communication, and the field of home network and information appliance.
FIG. 1 is a conceptual diagram illustrating data and beacon transmission/reception scheme of a WPAN according to the related art. Here, a basic element of the WPAN is referred to as a station.
The WPAN is formed when two or more stations that operate at the same radio frequency channel are present within a personal activity region. Such stations are classified into a master 10 and a slave 20 according to operations thereof.
The master 10 manages the entirety of a piconet, and only one master exists in the piconet.
The piconet is a wireless communication network formed by various independent communication devices using a Bluetooth technology or a UWB communication technology. Devices for forming such a network act as a master or a slave by a control protocol according to a situation.
The piconet is formed in a small space within a radius of several tens of meters and includes both a stationary device and a moving device. According to the piconet, unlike a wireless local area network (WLAN), a base structure for transmission is not preset, but a network between devices is formed by a control protocol according to a situation.
As illustrated in FIG. 1, the master 10 broadcasts a beacon to the slave 20 to control the slave 20, and the slave 20 transmits/receives data according to control by the master 10.
The WPAN illustrated in FIG. 1 is an autonomous network in which devices are able to wirelessly communicate with each other without an access point (AP).
That is, the WPAN according to the related art, which is an ad-hoc-based network for peer-to-peer (P2P) communication, is different from an infrastructure-based network, e.g., a WiFi network, in which devices communicate with each other through an AP.
In the case where the piconet is configured at a specific channel as illustrated in FIG. 1, communication between a master and a slave and communication between slaves may be freely performed. However, for convenience, it is assumed that a star-type application in which communication is only performed between the master 10 and the slave 20 is used as illustrated in FIG. 2.
Regarding an application for communication between the master 10 and the slave 20 using the WPAN according to the related art, when frequency interference on a specific channel occurs, the entire network needs to be moved to another adjacent channel which is free from frequency interference.
FIG. 3 is a conceptual diagram illustrating master-directed channel switching according to the related art which has been proposed to satisfy the above-mentioned necessity.
According to the master-directed channel switching technology of FIG. 3, in the case where a channel is switched, due to occurrence of channel interference, by using a network control function provided by the WPAN, the master 10 scans adjacent channels, and switches a channel of the entire network to a candidate channel that is determined as being least affected by interference on the basis of information on the scanned adjacent channels.
That is, when channel interference occurs on channel 2 at which the mater 10 and the slave 20 communicate with each other, the mater 10 scans adjacent channels, and switches the channel to channel 9 that is determined as being least affected by interference from among the scanned channels.
However, according to the related art, when the mater 10 scans adjacent channels to detect states thereof, all slaves 20 connected to the mater 10 are disconnected from the network, causing communication interruption.
Furthermore, after a channel of the entire network is switched, it takes long time for the slaves 20 disconnected from the network to be reconnected to the master 10. Therefore, a time of communication interruption between the master 10 and the slaves 20, i.e., a time taken until the channel switching is completed after the master 10 scans adjacent channels, becomes long.
Therefore, it may be difficult to apply the master-directed channel switching technology of the related art to an application sensitive to time delay.